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BEST AVAILABLE com W. R. CLARK MANUFACTURE OF ELECTRIC FURNACE LININGS July 17, 1923. 1,461,863

Original Filed Aug. 6, 1917 avwe wfoz BEST AVAILABLE COP.

Patented July 17, 1923.

UNITED STATES PATENT OFFICE.

WALTER R. CLARK, OF BRIDGEPORT, CONNECTICUT, ASSIGNOR TO BRIDGEPORT BRASS COMPANY, OF BRIDGEPORT, CONNECTICUT, A CORPORATION OF CONNECTICUT.

MANUFACTURE OF ELECTRIC-FURNACE LININGS.

Original application filed August 6, 1917, Serial No. 184,675. Divided and this application filed September 8, 1919.

To all whom it may concern:

Be'it known that I, WALTER R. CLARK, a citizen of the United States, residing in Bridgeport, in the county of Fairfield and State of Connecticut, have invented certain new and'useful Improvements in Manufacture of Electric-Furnace Linings, of which the following is a full, clear, and exact description.

This invention relates to the manufactur of electric furnace linings and the case is a division of my application Serial No. 184:,67 5, filed August 6, 1917.

The invention has particular reference to the manufacture of induction furnaces of the type in which a channel or passage of closed cross-section, communicating with the hearth or chamber at two points, receives a portion of the molten bath, which acts as the secondary of the transformer. The channel or passage through which the metal of the secondary flows is usually formed of or lined with a suitable refractory insulating material, which will satisfactorily Withstand the high temperature developed in the operation of the furnace.

One of the primary objects of the present invention is to overcome the disadvantages incidental to the employment of a solid metal templet or pattern, such as has been used in the construction of furnaces of this character. These solid metal templets have in some cases been constructed wholly of brass where the furnace was designed for the melting of brass scrap or the like, and it has been customary to leave the pattern or templet in place in a secondary passage after the latter has been formed by tamping the refractory material about the templet or pattern, the latter being utilized when the completed furnace is first placed in operation. Where such a solid brass templet is used, however, certain drawbacks arise from the expansion which is incident to heating the templet to the melting point, which ex pansion is considerable and is apt to crack, fissure or otherwise injure the lining of the secondary passage, that usually has a different coefficient of expansion.

The primary object of my present invention is to obviate this disadvantage and to facilitate the manufacture of induction furnaces of the type above described.

Another object of the invention is to fur- Serial No. 322,556.

nish an improved form of templet or form for use in such manufacture. My improved templet, which can be very readily constructed, neither injuriously afiects the lining of the furnace, nor the metal or alloys which are melted in the furnace. The templet is sufficiently hard and strong at ordinary temperatures, however, to enable the refractory material to be tamped or rammed about it in a very convenient and satisfactory manner.

To these and other ends, the invention consists in the novel features and procedure hereinafter described and claimed.

In the accompanying drawing:

F ig. 1 is a vertical central section of an induction furnace, showing my improved templet in position in the secondary channel.

F g. 2 is a section on line 22 of Fig. 1.

Fig. 3 is a detail of the templet.

Fig. 4 is an enlarged cross-section taken through one leg of the templet; and

Fig. 5 is a similar section taken through the leg of the templet of somewhat modified character.

In the drawing, I have shown an electric induction furnace having a body 10 composed of a metal jacket or casing 11, and a refractory lining 14. The furnace has a basin or hearth 13 at the upper part, which in this case is formed in a layer or body of refractory material packed within a layer 12 of suitable heat insulating material, such for example as infusorial earth. The layer 14 advantageously consists of a suitable asbestos cement, although I do not limit myself in this respect. The hearth has a pouring spout 15 and a charging opening 16, having a door 17. Beneath the hearth of the furnace shown herein is a closed channel of approximately V-shape, indicated at '18, having substantially straight side portions communicating with each other at an acute angle, as shown at 19, and connecting with the hearth at opposite sides of the latter, as shown at 20. The metal which is reccived in the channel 18 in the operation of the furnace acts as a secondary of a trans former whose primary is constituted by a horizontally arranged core 21 extending about the upper portion of the channel 18 and having a winding 21 suitably connect ed with a source of current. Owing to the arrangement of the two legs of the channel 18, at an acute angle to each,- other, the action of the primary is such as to set up a thorough circulation of molten metal in the channel and the bath or pool in the hearth, it being understood, of course, that in practice the upper ends of the continuous channel are in constant communication with the lower part of the hearth which is filled to approximately the level of the pouring spout with a bath of molten metal.

In, constructing the lower portion of a furnace such as that selected for illustration, I use a pattern, templet or form 22 for the; construction of the channel 18 in the refractory material. In this instance, the templet, which is of the same shape as the passage or channel which it is desired to. form, consists of a hollow body or tube 23 ofibrass, copper, or other suitable metal hayingan interior filling In the example shown in Figs. 1 to a, the filling consists of so-called parafiin, wax or like hydrocarbon. The templet is held in position in a suitable frame, andthe: refractory material, such as asbestos cement, in which the secondary channel is. to be formed, is tamped or rammed about the templet, The latter is sufiicientlyhard and, strong at ordinar tenn peratures'to allow the refractory material to be firmly packed.- or rammed around it, soastq obtain. achannel of uniform crosssection having a. smooth homogeneous surface. The interior filling- 2& of the templet is hard enough at ordinary temperatures to afiord a very firm and substantial backing. forthe wall of the relatively thin tube, whereby the collapse of such tubeis prevented. After'theramming operation has been com leted, the furnace structure, is then (.11 2 Itmay be dried in a suitable oven. 01; kiln, for'example, and when so. dried, the heat melts the wax and causes it to flow. out of the ends of the templet tube Or, it desired, an electric current; can be. passedthrough. the tube from an exterior source, orecurrent can be induced in the. tube by theuseofthe transformer for the purpose of melting and eliminating the templet core or filling. If the filling is eliminated electrically-,the ends of the tube may be connected to the poles of an exterior source of currenhor the transformer may be utilized: if the ends of the tube are suitably interconnected soas to provide a closed circuit.

After melting out the wax or other filler, the circulation of the current in the tube may be continued for the purpose of dryingout the lining of the passage.

In startingthe furnace, molten metal is poured into the furnace chamber and the same completes the secondary in an obvious manner. The tubularmetallic remnant of the templet remaining in the furnace is prefferably melted before additional metal is poured in and in melting the tube (by plication. of

BEST AVAlLABLE COP\ means of the transformer); thereis no, deleterious effect upon the lining, owing'to the fact that the tube is then free to collapse in an inward direction. In other words, there will be no injurious pressure exerted by the tube in an outward or lateral direction as a result of the expansion incidental to the heating of the tube to the melting point. The tube can advantageously"be made of copper, so as to provide for a maximum expansion or the extension of the same without rupture and at the same time owing to the character of the templet, s'uch expansion or extension will not injure the lining. f brass is to be melted in the furnace, moreover, the copper will alloy itself readily with the charge.

In. the modification. shown in Fig. 5, the templet consists of the comparativelythin metal tube similar to that previously: de-

scribed, with a filling 25 of sand, which is another material that reinforces the tern,- plet interiorly to, such an extent to offer sufiicient resistance in ramming; When, the operation of .ramming'has' been con'ipleted, the sand can be run out of the tube very readily by turnin' 'it upside down, as will be understood; lhetubular metalportion of the templetis then to collapse inwardly so that there-I of, in expanding under theapp ifdafiioni of heat, will not exert, in'i'uriouspres'suifeion the lining of the secondary passage Various changes maybe", arena-1 tails of the procedure, and inltlie', pletj or form, without departing fioin the so "e as. thc passage to. be formed, and'which is;

made at Iea'stpartIy offa'pliiivbl, 'adil'yl meltable, nonrmetal lic s'olidfirhi'cli'. Sui-Z ticiently hardv and, strong-to. ,resisti Ill Shore; tion undertlie? proper 'ta nping lpressnre; and their melting such ftp;- heat, as claimed in thesparent; application. I A I lVhatI claim is: ,7 l. The method ofinakingthe refractory structure. of an electric =fu,rna.ce ,o1: tlie" like; having passage of channel, whichlcqmi prises tampingrefractory materialhhont a. templet of the same shape as thepassage to, be formed, and consisting 'of" a inetallic outer part temporarily reinforced with in fillin so that such. templet. ispsnflicientlyf hard and strong to resist. collapsefiind'ei: tamping pressure, and then eliminatingtlie filling material. 7 i i I 2. The method of making the refractory structure of an electric furnace or the like having a passage therein, which comprises ramming refractory material about a templet of the same shape as the passage to be formed, consisting of a metallic outer part and an inner readily meltable filling which supports the outer part under tamping pressure, and then melting out the filling material.

The method of making the refractory structure of an electric furnace or the like having a passage or channel therein, which comprises tamping refractory material about a hollow templet of the same shape as the passage to be formed, having an interior filling, and then removing the filling from the templet.

4. The method of making the refractory structure of an electric furnace or the like having. a passage or channel therein, which comprises ramming refractory material about a templet of the same shape as the passage to be formed, having an interior filling of readily meltable material, and then eliminating the filling by melting.

5. The method of making the refractory structure of an electric furnace or the like having a passage or channel therein, which comprises ramming refractory material about a templet of the same shape as the passage to be formed, comprising an outer comparatively thin metal tube with an interior filling, and then removing the filling.

6. The method of making the refractory structure of an electric furnace or the like having a passage or channel therein, which comprises ramming refractory material about a templet of the same shape as the passage to be formed, having within its periphery or circumference a body of nonmetallic material, which at ordinary temperatures is sufliciently hard and strong to resist collapse under tamp-ing pressure, but which melts at a low temperature, and then applying heat to the structure for eliminating such non-metallic material.

7. The method of making the refractory structure of an electric furnace or the like having a passage or channel therein, which comprises tamping refractory material about a templet of the same shape as the passage to be formed, consisting of an outer part open at at least one end and an inner body of filling material adapted to be run out of the open end-of the templet, and then running the interior filling out of the templet.

8. A templet for the manufacture of electric induction furnaces and the like, comprising a hollow body having an interior filling of readily meltable material.

9. A templet for the manufacture of electric induction furnaces and the like, having within its crosssection a body of wax.

BEST AVAILABLE COFW 8 10. A templet for the purpose described, consisting of an outer part open at at least one end, and an interior filling.

11. A templet for the purpose described, comprising a metallic outer part and a nonmetallic interior filling.

12. A templet for the purpose described, comprising a metallic tube.

13. A templet for the purpose described. comprising a metallic tube, and with an interior temporary filling.

14. A templet for the purpose described, comprising a metallic tube, and with an interior temporary filling of wax.

15. The method of drying a green refrae tory structure, which comprises the location of a collapsible electric conductor tube within and in contact with the refractory body. and the passage of an electric current through said conductor tube, whereby, on the heating of such tube, for drying the refractory structure, the lateral pressure on the latter is minimized.

16. A templet for the purpose described constructed in the form of a tube with an open end, and a filling adapted to be run out of such open end.

17. A templet for the purpose described constructed in the form of a tube with an open end, and a filling adapted to be run out of such open end, such filling consisting of a waxy substance.

18. The method of drying a green refrac toryl structure, which comprises the location of a temporarily filled collapsible electric conductor within the refractory body, and the induction of current in said conductor for eliminating the filling Of such conductor and thereby permitting the inward expansion of the latter to relieve pressure on the refractory walls due to the heating effect.

19. The method of making the refractory structure of an electric furnace or the like having a passage therein, which comprises ramming refractory material about a conductor tube having an interior filling of lower melting point than the tube, and then eliminating the filling by'melting.

20. A templet for the purpose described, consisting of a conductor tube having a temporary, low melting point core.

21. The method of making a refractory the refractory material,

23. The method of making the refractory structure of an electric furnace or the like having a passage therein which comprises ramming refractory material about a h0l,-

low conductor having an interior filling, of lower melting point than the conductor, and then liminating the filling by'melting while leaving the conductor in the passage.

24. A teniplet, for the purpose described, consisting of a hollow conductor having a temporary low melting point core.

25. The method which comprises forming the refractory structure of an electric furnace or the like, having a passage therein, by ramming refractory material about a metal conductor of electricity having an interior filling of lower melting pointthan the conductor body, eliminating the filling by melt eEerAvAlLAeLE coex 7 ing, and then utilizing the remaininghollow conductor body in the operation of the furnace to create an electrical circuit through the passage. i

26. The method which consists in making the refractory structure, of an electric furnace or tllfiililie by tamping'operations, in volving the tamping of refractory material ab'outa hollow, metallic conductor of eleceliminating the filling by .melting, While leaving the conductor body in'situ in the refractory structure, drying'the Walls of the passage in which the conductor body is located, and utilizing the conductor body for WALTER R CLARK.

tricity, having an interior fillingot lower melting po1nt than the conductor body, then 

